Anal cancer is an uncommon malignancy that starts in the anus -- the opening at the end of the rectum.
The American Cancer Society estimates that 7,210 cases of anal cancer will be diagnosed in 2014 and about 950 deaths will occur that year from anal cancer.
By contrast, some136,830 people are predicted to be diagnosed with colorectal cancer in the U.S. in 2014, and about 50,310 people are predicted to die of the disease that year.
Approximately half of all anal cancers are diagnosed before the malignancy has spread beyond the primary site, whereas 13% to 25% are diagnosed after the cancer has spread to the lymph nodes, and 10% are diagnosed after the cancer has spread to distant organs, or has metastasized.
When it is found early, anal cancer is highly treatable.
The overall five-year survival rate following diagnosis of anal cancer is 60% for men and 71% for women.
When the cancer is diagnosed in its earliest stage, five-year survival rate is 82%. Once the cancer has spread to surrounding lymph nodes, the five-year survival drops to 60%. If the cancer has spread to distant organs, about one in five patients lives for five years or more.
Anal cancer may be detected during a routine digital rectal exam or during a minor procedure, such as removal of what is believed to be a hemorrhoid.
The cancer may also be detected with more invasive procedures such as an anoscopy, proctoscopy, or endorectal ultrasound.
If cancer is suspected, a biopsy should be done and the specimen examined by a pathologist.
Staging workup should include an abdominal and pelvic CT scan or a pelvic MRI scan to assess the pelvic lymph nodes, a chest x-ray, and liver function studies. PET scanning is not necessary.
How Is Anal Cancer Treated?
Anal cancer is primarily treated with a combination of chemotherapy and radiation. This reduces the need for a colostomy and carries a 5-year survival rate of over 70%. The treatment of anal cancer, in this fashion, has not changed since 1974.
Surgery is reserved only for patients failing the above therapy. Salvage therapy has resulted in a 60% 5-year survival rate.